This is Settings UI issue instead of Blink's spell checker.

There is no editDictionary option on Mac. Able to repro this on the latest canary(60.0.3110.0) of Linux Ubuntu 14.04.

Just to update, bisect is in progress for this.

Using the per-revision bisect providing the bisect results,
Good build: 60.0.3109.0 (Revision: 474118).
Bad build : 60.0.3110.0 (Revision: 474499).
You are probably looking for a change made after 474420 (known good), but no later than 474421 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/5a59f95a0fcbaa5976fa7e7247f77f430d9d041a..6997a3932e8fac115ef30c14a3c02178144dabf0

@scottchen: Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.
Thank You.

Investigated, this is not a regression issue. 

Previously in M59 (and also in settings-frame), if you try to add a long word, the interface will show the word "as though it had been added" into the dictionary, but in reality the word was not really committed into the dictionary, so if you refresh the page you'll see that the word isn't there.

My CL shown in the bisect only exposes this issue, since it doesn't "fake add" the word in the front-end anymore.

I suggest to make a new/repurpose this bug as "show an error message when the word is too long for the spell check dictionary."

 Issue 768768  has been merged into this issue.

tbuckley@ any thoughts on this?

Good point re #7, we should (1) turn the underline red and (2) disable the "Add word" button when the input is invalid. It seems like any words that are too long or strings that have spaces in them are considered invalid, though there may be more cases.

Removing regression tag based on #7.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f82d5908b057ffd5749c91428855465294dab91f

commit f82d5908b057ffd5749c91428855465294dab91f
Author: Scott Chen <scottchen@chromium.org>
Date: Fri Jan 12 19:47:41 2018

MD Settings: add error handling for spell-check add-word page

TBR=groby

Bug:  726279 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If98b70dd2aa8ab652a515092b52264365364941f
Reviewed-on: https://chromium-review.googlesource.com/848305
Commit-Queue: Scott Chen <scottchen@chromium.org>
Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#529029}
[modify] https://crrev.com/f82d5908b057ffd5749c91428855465294dab91f/chrome/app/settings_strings.grdp
[modify] https://crrev.com/f82d5908b057ffd5749c91428855465294dab91f/chrome/browser/resources/settings/languages_page/edit_dictionary_page.html
[modify] https://crrev.com/f82d5908b057ffd5749c91428855465294dab91f/chrome/browser/resources/settings/languages_page/edit_dictionary_page.js
[modify] https://crrev.com/f82d5908b057ffd5749c91428855465294dab91f/chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc
[modify] https://crrev.com/f82d5908b057ffd5749c91428855465294dab91f/components/spellcheck/common/spellcheck_common.h

Tested the issue on Windows 10 and Ubuntu 14.04 using Chrome version M65 - 65.0.3322.0. Now on entering long data[used Google is an American multinational technology company specializing in Internet-related services and products. These include online advertising technologies, search, cloud computing, software, and hardware.Wikipedia] --- Add Word button is seen disabled, cannot exceed 99 letters error message is seen along with red underline as per change mentioned in comment#11 and #13.

Hence the fix is working as expected. Adding TE-Verified label. Attaching screenshot for reference.

Thank you!

Deleted: Issue 726279.png 119 KB

	Issue 726279.png 119 KB View Download